The current program relies heavily on the ability to produce recombinant monoclonal antibodies by transient transfection. Drs. Steinman and Ravetch will make use of such reagents in targeting DC subsets in vivo and in producing modified antibodies that are capable of DC targeting and activation. Because they will be used in vivo and in tissue culture experiments uniform quality control for these reagents including LPS testing will be critical. Dr. Nussenzweig will produce hundreds of different human monoclonal antibodies by the same transfection method in his part ofthe program for testing in HIV binding and neutralization assays. These assays will require hundreds of micrograms of the antibody reagents. The proposed core will produce recombinant antibodies for all ofthe participants in the program and in addition store and distribute the reagents to collaborators and to the scientific community